When transporting goods, for instance, on cargo ships, trains and trucks, part-load, freight and thermo-containers are used to a great extent. Such containers are easy to handle in loading and unloading due to standardized sizes and a robust construction that allows stacking of a plurality of containers on top of each other. Containers are stacked both during storage and transportation of containers. This design of containers, which are often referred to as ISO containers, allows the transported goods to be well protected in transport and also during loading and unloading.
Containers of the type described above are usually rectangular with floor, roof, two side walls and two end walls. One end wall usually consists of a door portion which is often formed as a pair of doors. Corner fittings with oval holes are usually arranged at the corners of the container and allow connecting and lashing of containers.
To connect and lash two or more containers, use is made of equipment comprising a lockable coupling which can be inserted into and locked to a corner fitting of an ISO container. WO2004/020316 discloses a hook shaped coupling for connecting two containers to each other, the containers are connected to each other by lowering the upper container and at the same time rotating it around a central vertical axis for achieving a simultaneous movement at all four corners of the container corresponding with the geometry of the hook shaped coupling. The upper container is released by lifting and at the same time rotating the upper container around a central vertical axis. In this way all four hooks are released at the same time and with a movement reversed in relation to the movement for connecting of the two containers.
Transport systems of today, for example ships, can take several thousands of containers, the containers are stacked on top of each other in order to efficient use the available space. For this method of loading to be safe in transport, each container is connected to at least one neighbouring container, or to the transport vehicle, by means of, for example, lockable couplings. Consequently, the stacked containers are locked to each other and to the transport vehicle, thereby providing a stable connected three-dimensional transport stack.
It is currently usual that thousands of containers are used at one ship. This means that small reductions of the time used during handling of each container may yield considerable saving of time and hence economic profit in the end.
It is desirable with fast and efficient loading and unloading of containers, it is also desirable to minimize the need of personnel during loading and unloading of containers. There is today container couplings which does not need to be manually operated after/during connection or disconnection of two containers. But there is problems with this kind of container couplings, if for example the loaded/unloaded ship is tilting during loading/unloading it will problems to connect the containers since the couplings at all four corners of the container has to engage simultaneously. The same problem will occur if the movements of the crane are not exact enough.
The above described container couplings, according to prior art, does only transfer forces between connected containers on one side of the hole of the corner fitting, for example during displacement of the containers at sea (due to waves, wind etc.).
It is thus desirable to provide a coupling which that is fast and efficient to handle during loading and unloading.